projects/linux·blob v2.6.28-rc8 · refs

229 lines · 4.8 KiB

1/*
2 * Handling of different ABIs (personalities).
3 *
4 * We group personalities into execution domains which have their
5 * own handlers for kernel entry points, signal mapping, etc...
6 *
7 * 2001-05-06 Complete rewrite, Christoph Hellwig ([email protected])
8 */
9
10#include <linux/init.h>
11#include <linux/kernel.h>
12#include <linux/kmod.h>
13#include <linux/module.h>
14#include <linux/personality.h>
15#include <linux/proc_fs.h>
16#include <linux/sched.h>
17#include <linux/seq_file.h>
18#include <linux/syscalls.h>
19#include <linux/sysctl.h>
20#include <linux/types.h>
21
22
23static void default_handler(int, struct pt_regs *);
24
25static struct exec_domain *exec_domains = &default_exec_domain;
26static DEFINE_RWLOCK(exec_domains_lock);
27
28
29static u_long ident_map[32] = {
30 0, 1, 2, 3, 4, 5, 6, 7,
31 8, 9, 10, 11, 12, 13, 14, 15,
32 16, 17, 18, 19, 20, 21, 22, 23,
33 24, 25, 26, 27, 28, 29, 30, 31
34};
35
36struct exec_domain default_exec_domain = {
37 .name = "Linux", /* name */
38 .handler = default_handler, /* lcall7 causes a seg fault. */
39 .pers_low = 0, /* PER_LINUX personality. */
40 .pers_high = 0, /* PER_LINUX personality. */
41 .signal_map = ident_map, /* Identity map signals. */
42 .signal_invmap = ident_map, /* - both ways. */
43};
44
45
46static void
47default_handler(int segment, struct pt_regs *regp)
48{
49 set_personality(0);
50
51 if (current_thread_info()->exec_domain->handler != default_handler)
52 current_thread_info()->exec_domain->handler(segment, regp);
53 else
54 send_sig(SIGSEGV, current, 1);
55}
56
57static struct exec_domain *
58lookup_exec_domain(u_long personality)
59{
60 struct exec_domain * ep;
61 u_long pers = personality(personality);
62
63 read_lock(&exec_domains_lock);
64 for (ep = exec_domains; ep; ep = ep->next) {
65 if (pers >= ep->pers_low && pers <= ep->pers_high)
66 if (try_module_get(ep->module))
67 goto out;
68 }
69
70#ifdef CONFIG_MODULES
71 read_unlock(&exec_domains_lock);
72 request_module("personality-%ld", pers);
73 read_lock(&exec_domains_lock);
74
75 for (ep = exec_domains; ep; ep = ep->next) {
76 if (pers >= ep->pers_low && pers <= ep->pers_high)
77 if (try_module_get(ep->module))
78 goto out;
79 }
80#endif
81
82 ep = &default_exec_domain;
83out:
84 read_unlock(&exec_domains_lock);
85 return (ep);
86}
87
88int
89register_exec_domain(struct exec_domain *ep)
90{
91 struct exec_domain *tmp;
92 int err = -EBUSY;
93
94 if (ep == NULL)
95 return -EINVAL;
96
97 if (ep->next != NULL)
98 return -EBUSY;
99
100 write_lock(&exec_domains_lock);
101 for (tmp = exec_domains; tmp; tmp = tmp->next) {
102 if (tmp == ep)
103 goto out;
104 }
105
106 ep->next = exec_domains;
107 exec_domains = ep;
108 err = 0;
109
110out:
111 write_unlock(&exec_domains_lock);
112 return (err);
113}
114
115int
116unregister_exec_domain(struct exec_domain *ep)
117{
118 struct exec_domain **epp;
119
120 epp = &exec_domains;
121 write_lock(&exec_domains_lock);
122 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
123 if (ep == *epp)
124 goto unregister;
125 }
126 write_unlock(&exec_domains_lock);
127 return -EINVAL;
128
129unregister:
130 *epp = ep->next;
131 ep->next = NULL;
132 write_unlock(&exec_domains_lock);
133 return 0;
134}
135
136int
137__set_personality(u_long personality)
138{
139 struct exec_domain *ep, *oep;
140
141 ep = lookup_exec_domain(personality);
142 if (ep == current_thread_info()->exec_domain) {
143 current->personality = personality;
144 module_put(ep->module);
145 return 0;
146 }
147
148 if (atomic_read(&current->fs->count) != 1) {
149 struct fs_struct *fsp, *ofsp;
150
151 fsp = copy_fs_struct(current->fs);
152 if (fsp == NULL) {
153 module_put(ep->module);
154 return -ENOMEM;
155 }
156
157 task_lock(current);
158 ofsp = current->fs;
159 current->fs = fsp;
160 task_unlock(current);
161
162 put_fs_struct(ofsp);
163 }
164
165 /*
166 * At that point we are guaranteed to be the sole owner of
167 * current->fs.
168 */
169
170 current->personality = personality;
171 oep = current_thread_info()->exec_domain;
172 current_thread_info()->exec_domain = ep;
173
174 module_put(oep->module);
175 return 0;
176}
177
178#ifdef CONFIG_PROC_FS
179static int execdomains_proc_show(struct seq_file *m, void *v)
180{
181 struct exec_domain *ep;
182
183 read_lock(&exec_domains_lock);
184 for (ep = exec_domains; ep; ep = ep->next)
185 seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
186 ep->pers_low, ep->pers_high, ep->name,
187 module_name(ep->module));
188 read_unlock(&exec_domains_lock);
189 return 0;
190}
191
192static int execdomains_proc_open(struct inode *inode, struct file *file)
193{
194 return single_open(file, execdomains_proc_show, NULL);
195}
196
197static const struct file_operations execdomains_proc_fops = {
198 .open = execdomains_proc_open,
199 .read = seq_read,
200 .llseek = seq_lseek,
201 .release = single_release,
202};
203
204static int __init proc_execdomains_init(void)
205{
206 proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
207 return 0;
208}
209module_init(proc_execdomains_init);
210#endif
211
212asmlinkage long
213sys_personality(u_long personality)
214{
215 u_long old = current->personality;
216
217 if (personality != 0xffffffff) {
218 set_personality(personality);
219 if (current->personality != personality)
220 return -EINVAL;
221 }
222
223 return (long)old;
224}
225
226
227EXPORT_SYMBOL(register_exec_domain);
228EXPORT_SYMBOL(unregister_exec_domain);
229EXPORT_SYMBOL(__set_personality);